3. (15 Points) One coin is said to be unfair if P (Head) is not equal to P (Tail). Now we have a unfair coin A where P(Head) = 0.3. Let X as one random variable defined by X("Head") = 1 and X("Tail") = 0. (1) Compute the expected value and variance of X. (2) Compute the expected value and variance of X2. (3) Compute the expected value and variance of X. If we toss the coin A for 3 times sequentially, (4) what are sample space? How many compound events? (5) What is the probability of the event "The number of occurrence of Head is no less than the number of occurrences of Tail"? (Hint: you can use tree diagram or combinatorial rule.)